1. Technical Field
The present disclosure relates to reducing power consumption in wireless communication devices, and more particularly to reducing power consumption in full-duplex cellular telephones as a result of an in-circuit determination of a transmitter-to-receiver isolation parameter.
2. Background Information
In a typical cellular telephone handset, a large portion of the cellular telephone's battery energy (about sixty percent) is consumed by the RF transceiver. Within the RF transceiver, power consumption is almost equally split between the transmit signal path and its transmit local oscillator and the receive signal path and its receive local oscillator. A typical cellular telephone consumes 100 mA, and a typical cellular battery has 800 mA-hours of capacity, so the typical cellular telephone has a talk time of approximately eight hours. Extending this talk time is desired.
Several methods and techniques have been developed to reduce power consumption in these portions of the RF transceiver that consume the bulk of the battery energy. Some of these methods and techniques involve power biasing different parts of the transceiver in different ways and at different levels depending on the operating environment of the cellular telephone. For example, if no jammer is detected or if the cellular telephone transmitter is not active, then transceiver circuitry may be powered at a lower level whereas if a jammer is detected or if the transmitter is active then the circuitry is powered at a higher level. U.S. Patent Application Publication 2005/0134336 discloses a method for dynamically setting a bias current within a receiver depending on whether a jammer is detected. U.S. Pat. No. 7,283,851 discloses reducing a bias current within a receiver depending on the operating condition of the receiver. Although these techniques function well in certain types of cellular telephones, the use of these techniques is often limited or precluded in other types of cellular telephones. For example in a full-duplex W-CDMA air interface system (Wideband Code Division Multiple Access), the Phase-Locked Loops (PLLs) of the receive and transmit local oscillators within the transceiver generally must remain locked during receive and transmit.